The present invention, in some embodiments thereof, relates to medical techniques. More particularly, but not exclusively, the present invention relates to the devices and methods for use in surgery and in emergency and military medicine.
Arterial tourniquets have been used in surgery, emergency and military medicine for over 300 years for an emergency treatment of shock caused primarily by loss of blood through internal bleeding or injury of the human body (see U.S. Pat. Nos. 34,112; 35,038). The term shock, used for more than 150 years, was defined to characterize the alarming symptoms known as a result of a wide variety of causes, both physical and psychological. One of the most frequently encountered types of shock is the traumatic one, caused after a severe injury. As a result of the injury, a disturbance of fluid balance occurs which is manifested by a decreased volume of blood and tissue perfusion.
It is generally accepted that the application of an arterial tourniquet to a limb to prevent bleeding or establish a bloodless surgical field must be limited in time irreversible damage to the limb is to be prevented.
U.S. Pat. No. 4,294,261 “Logic-controlled occlusive cuff system” describes a system that comprises a pressure cuff and a source of regulated compressed gas feeding the cuff through an electrically-operated fill valve. In response to an external start signal, a logic network starts the pressurization cycle and a timer. A pressure transducer continuously monitors the pressure in the cuff. The timer, after a selected time delay, opens the vent valve to the ambient pressure, thereby ending the pressurization cycle.
U.S. Pat. No. 4,321,929 “Tourniquet” disclosed an automatic tourniquet which has a control system therefore. An electronic sensing means senses physiological variables and generates signals which are applied to the computer or microprocessor, which analyzes such signals and generates control signals for controlling the motors operating pumps. A tourniquet has a timer is connected for controlling same and providing intervals of time during which blood pressure is sensed and the tourniquet is tightened.
U.S. Pat. No. 6,746,470 and US 2003/0139766 “Emergency and Military Tourniquet for Pre-Hospital Use” disclose a pneumatic tourniquet adapted for self application by an injured person in a military or emergency situation to stop blood loss from an injured limb. A tourniquet comprises a bladder cuff with a clamp means for securing the bladder around the limb and an indicator module connected to the bladder. The indicator module is indicates cuff pressure and elapsed inflation time interval up to 2 hours and is supplied with a microprocessor and an alarm indicator that provides an audible and visual indication of alarm to the crew or user. The microprocessor is programmed to determine elapsed inflation time by measuring the duration of time that the pressure has exceeded a predetermined pressure threshold. The alarm indicator may also be activated by microprocessor if unusually high pressures are detected in the bladder (for example pressures greater than 400 mmHg).
U.S. Pat. No. 6,149,666 disclosed a tourniquet includes an elongate flexible body having an electronic lead and a pair of spaced-apart connection location for attachment to secure the body in circumscribing relationship about the limb. The tourniquet is provided also with a microchip and a timer for generation of an alarm signal upon passage of an elapsed time. The microchip and timer may be modified to include a wide variety of audio signals at various desirable periods of time.